The word stamina entered English in the late 17th century from Latin, where the plural 'stamina' meant the 'warp threads' on a loom, the foundational longitudinal fibers that give fabric its strength and stability. This concrete meaning derived from the verb 'stāre' (to stand), as these threads stand firm under tension. By the 18th century, the term was metaphorically extended in English to refer to the vital, sustaining forces of an organism—its "fibers of life." The modern abstract sense of enduring physical or mental energy and resilience logically evolved from this idea of the fundamental, standing strength within a person or thing.

Structure: stam (thread, fiber) + ina (noun suffix) 'stam' is from Latin 'stāmen', meaning 'thread of the warp, fiber', from the verb 'stāre' (to stand). The suffix '-ina' is a Latin noun-forming suffix.